What pitch of the roof, how many layers of shingles currently on the roof, any dormers, valleys, what style of roof, access around the house, etc.? All of these play into the cost.
Back when I was roofing a 31 sq house with a 6/12 pitch with access to boom the shingles onto the roof and no extra valleys or roof lines and only 1 layer of existing shingles would charge the cost of the shingles(approx $40-$50 sq) and the pitch x $10 to tear off and the same price to lay. 31 X $60 + 31 X $60 + 31 X shingle cost.
Prices definitely could have gone up since then.